Migrating my warehouse, when attempting to create a Index Server Catalog it willnot accept the catalog name "WHINDEX" states that "catalog name or location is already in use or invalid". There is also no option to rename the catalog. What is the fix or workaround?

The WHINDEX catalog can be safely deleted and re-created.
If you only move a portion of the warehouse to another location, you can simply play around with the "directories" of the catalog to reflect the correct locations.

The documentation on our support page gets into detail. Please look at this document: